Have scientists found any evidence for the origin of life?

Introduction

Both creationist and intelligent design writers assert that science has yet to understand the origin of life, and further claim that this is a fatal flaw in evolutionary theory [Behe1996; Dembski1998].

It is true that as of the present time, scientists do not yet fully understand biogenesis (as the origin of life is often termed). In particular, the origin of the first self-reproducing biomolecules, on which evolutionary processes could operate to produce more complicated systems, remains unknown. But numerous discoveries have been made in the area, including some rather striking results just in the past year or two.

Biogenesis from 1950 to 2000

The first major result in the field of biogenesis was a 1953 experiment by Stanley Miller and Harold Urey. In this experiment, the researchers tested an earlier hypothesis that conditions on the early earth may have favored the synthesis of organic compounds from inorganic compounds. They placed water plus some gases in a sealed flask, then passed electric sparks through the mixture to simulate the effects of sunlight and lightning. Over the next week or so, the mixture in the flask slowly turned a reddish-brown color. Upon analyzing the resulting “goo,” they discovered that it contained several amino acids, which are the building blocks of proteins [Davies1999, pg. 86-94]. The Miller-Urey experiment firmly established that basic biochemical building blocks such as amino acids can spontaneously form given the right conditions, although some researchers have questioned whether the Miller-Urey experiment is truly representative of what really happened on the early earth.

Going beyond the synthesis of basic amino acids, one leading hypotheses is that ribonucleic acid (RNA) played a key role. For example, researchers recently found that certain RNA molecules can greatly increase the rate of specific chemical reactions, including, remarkably, the replication of parts of other RNA molecules. Thus perhaps a molecule like RNA could “self-catalyze” itself in this manner, perhaps with the assistance of some related molecules, and then larger conglomerates of such compounds, packaged within simple membranes (such as simple hydrophobic compounds), could have formed very primitive cells [NAS2008, pg. 22]. Nonetheless, even the “RNA world” hypothesis, as the above scenario is popularly known, faces challenges.

21st century developments

A series of very interesting new results have been published in the field just in the past two or three years, and there is a sense in the field that progress is accelerating. Here is a brief summary of these results (as of early 2013):

In May 2009, a team led by John Sutherland, a chemist at the University of Manchester in England, solved a problem that has perplexed researchers for at least 20 years (see above), namely how the basic nucleotides (building blocks) of RNA could spontaneously assemble. As recently as a few years ago, the appearance of these nucleotides on the primitive earth was thought to be a “near miracle.” In the 2009 study, Sutherland and his team used the same starting chemicals that have been employed in numerous earlier experiments, but they tried many different orders and combinations. They finally discovered one order and combination that formed the RNA nucleotide ribocytidine phosphate. What’s more, when the mixture was exposed to ultraviolet light, a second nucleotide of RNA was formed. Two other nucleotides remain, but the synthesis of the first two was thought to be more difficult. Robert Shapiro pointed out that cyano-acetylene, one of Sutherland’s starting materials, is quickly destroyed and thus was not likely to have existed on the primitive earth, but Sutherland responded by pointing out that this chemical has been detected on Titan, so there is no reason to rule out its presence on the early earth [Wade2009].

In February 2010 scientists at the Scripps Research Institute in San Diego announced that they have synthesized RNA enzymes, known as ribozymes, that can replicate themselves without the help of any proteins or other cellular components. What’s more, these simple molecules can act as catalysts and continue the process indefinitely. The researchers began with ribozymes that occur naturally, and put these in a growth medium, where subsets “competed” with others. Eventually more successful (and more complex) ribozymes came to dominate the culture. As researcher Gerald Joyce noted, “The key thing is it replicates itself, and passes information from parent to progeny down the line. … Some functions are more fit than others, and those that are more fit ‘breed’ more, and are perpetuated more efficiently, and so it goes Darwinian.” [DaSilva2010].

Also in February 2010, researchers at the University of Colorado showed that a very simple RNA molecule can catalyze chemical reactions, without any other proteins present. Their form of RNA involved only five nucleotides. As researcher Michael Yarus noted, “This work shows that RNA enzymes could have been far smaller, and therefore far easier to make under primitive conditions, than anyone has expected.” [SD2010e].

In June 2010, a team of researchers at the Georgia Institute of Technology and the University of Roma La Sapienza succeeded in synthesizing guanine, one of the four bases of RNA. The other three, adenine, cytosine and uracil, have previously been synthesized. The researchers were able to form guanine by subjecting a solution of formamide (H2NCOH), a simple compound that often has been suggested as a starting material for biotic compounds, to ultraviolet radiation during heating. Thomas Orlando, one of the researchers, explained, “Our model prebiotic reaction is attractive because most aspects of the process were likely to occur on the early Earth and it reduces chemical constraints.” [SD2010a].

One aspect of the “RNA world” hypothesis that heretofore has stymied researchers is the difficulty in demonstrating that RNA molecules or components could form long, information-rich chains, in water solutions. In February 2013, a team of researchers at the Georgia Institute of Technology and the Institute for Research in Biomedicine in Barcelona, Spain announced that by giving a component of RNA known as TAP a “tail,” these units become “rosettes” that spontaneously form chains in water, like a large stack of plates, up to 18,000 units long. “The nice thing [about this study] is this is a demonstration of self-assembly in water,” noted Ramanarayanan Krishnamurthy, a chemist at the Scripps Research Institute in California. The next step will be to see whether such assemblies can encode information, as one possible chemical route to the origin of life [Service2013].

Further details on the search for the first self-replicating biomolecules are given in Origin.

Summary

It is undeniably true that scientists do not yet have a fully-developed chain of evidence for the origin of life — no knowledgeable scientist has ever claimed otherwise. Numerous scenarios have been explored, but there are still significant gaps in these theories.

Nonetheless, given the remarkable progress that has occurred in the biogenesis arena just in the past few years, it would be utter folly to presume that no additional progress will be made. Thousands of scientific papers, documenting countless experimental studies, have been published on these topics, and several previous show-stopping obstacles, such as the formation of certain building blocks of RNA, have been overcome. Almost certainly, even more remarkable results will be published in the next few years. There is not the slightest indication that fundamental, insuperable obstacles have been encountered in the field.

Given these developments, most observers, including the present author, believe that it is extremely unwise to base one’s religious or philosophical creed on the presumed impossibility of scientific research eventually discovering a complete natural process that could satisfactorily explain the origin or early development of life on earth. That would be a premier example of a “God of the gaps” theological error.

One fundamental difficulty with both the creationist and intelligent design approaches to the origin of life can be seen by considering the following “thought experiment.” Suppose a major international society announced that it had received a communication from a super-intelligent Entity, disclosing that this Entity had initiated or created life on earth. The next day inquisitive humans would then ask questions such as “What time frame was required for this creation?,” “What physical laws and processes were utilized by this Entity?,” “Can we replicate these processes in a laboratory?,” “Why was earth appropriate for life?,” “Was life similarly initiated or created elsewhere?,” “Who created this Entity?,” “Who created the universe?,” “Why?”

In other words, even if we found indisputable evidence that some supreme Entity had created life, virtually all of the fundamental questions of existence that have intrigued scientists and theologians alike for centuries would remain unanswered. In this light, the creationist-intelligent design approach of merely asserting “God did it,” and resisting deeper investigation, is tantamount to a “thinking stopper,” reveling in ignorance instead of thirsting for knowledge. Surely there is a more productive approach to harmonize science and religion.